U.S. patent application number 14/096294 was filed with the patent office on 2014-06-19 for power converter and its control method.
This patent application is currently assigned to Hitachi, Ltd.. The applicant listed for this patent is Hitachi, Ltd.. Invention is credited to Akira BANDO, Masaya ICHINOSE, Yasuhiro IMAZU, Yasuhiro KIYOFUJI, Akihiro MAOKA, Yasuhiro NAKATSUKA.
Application Number | 20140167701 14/096294 |
Document ID | / |
Family ID | 49918134 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140167701 |
Kind Code |
A1 |
NAKATSUKA; Yasuhiro ; et
al. |
June 19, 2014 |
Power Converter and its Control Method
Abstract
The invention provides a power converter including a plurality
of power conversion units each connected to a different feeder, a
DC energy interchange unit connected to the power conversion units
and connected to a secondary battery, and a power control unit
which instructs the regeneration-side power conversion unit
connected to the regeneration-side feeder of the feeders, through
which a regenerative current flows, and the consumption-side power
conversion unit connected to the consumption-side feeder through
which a current consumption flows, to output power from the
regeneration-side feeder to the consumption-side feeder through the
DC energy interchange unit. The power control unit also determines
the voltage of the DC energy interchange unit in such a manner as
to input/output energy corresponding to the sum of regenerative
power of the regeneration-side feeder and consumed power of the
consumption-side feeder to and from the secondary battery.
Inventors: |
NAKATSUKA; Yasuhiro; (Tokyo,
JP) ; IMAZU; Yasuhiro; (Tokyo, JP) ; MAOKA;
Akihiro; (Tokyo, JP) ; ICHINOSE; Masaya;
(Tokyo, JP) ; KIYOFUJI; Yasuhiro; (Tokyo, JP)
; BANDO; Akira; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi, Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Hitachi, Ltd.
Tokyo
JP
|
Family ID: |
49918134 |
Appl. No.: |
14/096294 |
Filed: |
December 4, 2013 |
Current U.S.
Class: |
320/134 |
Current CPC
Class: |
H02J 3/32 20130101 |
Class at
Publication: |
320/134 |
International
Class: |
H02J 7/02 20060101
H02J007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2012 |
JP |
2012-273156 |
Claims
1. A power converter comprising: a plurality of power conversion
units each connected to a different feeder; a DC energy interchange
unit connected to the power conversion units and secondary battery;
and a power control unit, wherein the power control unit instructs
a regeneration-side power conversion unit connected to a
regeneration-side feeder of the feeders, through which a
regenerative current flows, and a consumption-side power conversion
unit connected to the consumption-side feeder through which a
current consumption flows, to output power from the
regeneration-side feeder to the consumption-side feeder through the
DC energy interchange unit, and wherein the power control unit also
determines a voltage of the DC energy interchange unit in such a
manner as to input/output energy corresponding to the sum of
regenerative power of the regeneration-side feeder and consumed
power of the consumption-side feeder to and from the secondary
battery.
2. The power converter according to claim 1, wherein the DC energy
interchange unit includes means for measuring the voltage and is
connected with a communication line which transmits the measured
value of voltage to the power control unit.
3. The power converter according to claim 1, wherein the power
conversion units each include an instrument for measuring a current
flowing from the feeders to which the power conversion units are
connected, and wherein the power conversion units are connected
with a communication line transmitting the measured value of a
current to the power control unit and with the communication line
which receives a control value instructed from the power control
unit.
4. The power converter according to claim 1, wherein if a charge
amount of the secondary battery does not satisfy a predetermined
condition, the power control unit determines the voltage of the DC
energy interchange unit in such a manner as not to input/output the
energy corresponding to the sum of the regenerative power and the
consumed power to and from the secondary battery.
5. The power converter according to claim 1, wherein if the sum of
the absolute value of the regenerative power of the feeders on the
regeneration side is larger than the sum of the absolute value of
the consumed power of the feeders on the consumption side, and the
charge amount of the secondary battery is less than a maximum
charge amount, the power control unit determines the voltage of the
DC energy interchange unit so as to input energy to the secondary
battery, and wherein if the sum of the absolute value of the
regenerative power is smaller than the sum of the absolute value of
the consumed power, and the charge amount of the secondary battery
is greater than or equal to a target charge amount, the power
control unit determines the voltage of the DC energy interchange
unit so as to output energy from the secondary battery.
6. The power converter according to claim 1, further including a
secondary battery control unit which detects the charge amount of
the secondary battery.
7. The power converter according to claim 6, wherein if the charge
amount detected by the secondary battery control unit satisfies a
predetermined condition, the power control unit further controls
each of the power conversion units so as to input/output energy
corresponding to the sum of the regenerative power and the consumed
power of the feeders to and from the secondary battery.
8. The power converter according to claim 6, wherein the secondary
battery has a plurality of battery units connected in parallel, the
battery units each including battery modules connected in
series.
9. The power converter according to claim 8, wherein the DC energy
interchange unit includes a grounded central point, a positive
point to which a positive DC voltage is applied, and a negative
point to which a negative DC voltage is applied, and wherein the
battery units are each connected between the central point and the
positive point and between the negative point and the central
point.
10. The power converter according to claim 8, wherein the secondary
battery is provided with a switch circuit controlled by the
secondary battery control unit, and wherein the secondary battery
is capable of being separated from the DC energy interchange unit
for every battery unit.
11. The power converter according to claim 8, wherein the power
control unit further obtains operation information of a vehicle
driven by the power of the feeders and adjusts a target charge
amount of the secondary battery.
12. A power converter comprising: a plurality of power conversion
units each connected to a different feeder; a DC energy interchange
unit connected to the power conversion units; and a power control
unit which instructs the regeneration-side power conversion unit
connected to the regeneration-side feeder of the feeders, through
which a regenerative current flows, and the consumption-side power
conversion unit connected to the consumption-side feeder through
which a current consumption flows, to output power from the
regeneration-side feeder to the consumption-side feeder through the
DC energy interchange unit.
13. A power converting method for a power converter, the power
converter comprising a plurality of power conversion units each
connected to a different feeder, a DC energy interchange unit
connected to the power conversion units and connected to a
secondary battery, and a power control unit, the power control unit
performing the steps of: instructing the regeneration-side power
conversion unit connected to the regeneration-side feeder of the
feeders, through which a regenerative current flows, and the
consumption-side power conversion unit connected to the
consumption-side feeder through which a current consumption flows,
to output power from the regeneration-side feeder to the
consumption-side feeder through the DC energy interchange unit; and
determining the voltage of the DC energy interchange unit in such a
manner as to input/output energy corresponding to the sum of
regenerative power of the regeneration-side feeder and consumed
power of the consumption-side feeder to and from the secondary
battery.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a power converter capable
of mutually interchanging power between feeders and to a control
method for the power converter.
[0003] 2. Description of the Related Art
[0004] A regenerative brake refers to the application of brake by
using a motor normally employed as a drive source as a generator,
thereby converting kinetic energy into electrical energy and
recovering it. A recent railway vehicle has often been equipped
with the regenerative brake. Power regenerated by the regenerative
brake is consumed by another railway vehicle via a feeder.
[0005] There is described in the problems of the summary in
JP-2010-221888-A saying "provides an alternative current feeding
device which performs parallel feeding during sections of feeding
from two feeding substations different in power grid." In
JP-2010-221888-A "means for solving the problems" describes that
"there is provided an alternative current feeding device connecting
a first feeding section and a second feeding section, the
alternative current feeding device including a first AC-DC
converter connected to the end part of the first feeding section, a
second AC-DC converter connected to the end part of the second
feeding section, and a capacitive DC circuit connected between a DC
input/output end on the positive side in the first AC-DC converter
and a DC input/output end on the negative side in the first AC-DC
converter and further connected between a DC input/output end on
the positive side in the second AC-DC converter and a DC
input/output end on the negative side in the second AC-DC
converter".
[0006] There is described in the problems of the summary in
JP-2005-205970-A saying "maintains both of feeder terminal voltage
on both sides of a section post at a predetermined voltage and
enables effective utilization of regenerative energy". In
JP-2005-205970-A "means for solving the problems" describes that
"an AC-DC converter 42A is connected to a single-phase AC feeder
3A, and an AC-DC converter 42B is connected to a single-phase AC
feeder 3B so as to compensate a voltage fluctuation at feeder
terminal ends. At the same time, a DC-AC converter 42C is connected
between a DC circuit common to the converters (42A, 42B) and a
power storage element 44 to compensate a fluctuation in power
caused by the above feeder voltage compensation, thereby solving
the described problems."
SUMMARY OF THE INVENTION
[0007] Conventionally, power that a railway vehicle regenerates by
a regenerative brake flows through a feeder of the railway vehicle.
This regenerative power has been discarded wastefully where other
railway vehicles related to the corresponding feeder cannot consume
it.
[0008] In the invention described in JP-2005-205970-A, power is
mutually converted between two feeders and stored in a secondary
battery, thereby making it possible to store and effectively
utilize regenerative energy (regenerative power). In the invention
described in the JP-2005-205970-A, however, a power converter is
connected between the secondary battery and a DC circuit. There is,
therefore, a possibility that a power loss by the power converter
occurs.
[0009] In the invention described in JP-2010-221888-A, a power
converter that mutually converts power between two feeders is
equipped with a capacitive DC circuit including a secondary battery
to perform a power conversion between the two feeders. There is,
however, no disclosure on how to control the secondary battery to
store the regenerative power and how to effectively utilize the
regenerative power stored in the second battery.
[0010] Therefore, an object of the present invention is to provide
a power converter capable of interchanging and utilizing power
regenerated by an electric motor and to provide a control method
for the power converter.
[0011] In order to solve the above problems, the invention provides
a power converter including a plurality of power conversion units
each connected to a different feeder, a DC energy interchange unit
connected to the power conversion units and a secondary battery,
and a power control unit which instructs the regeneration-side
power conversion unit connected to the regeneration-side feeder of
the feeders, through which a regenerative current flows, and the
consumption-side power conversion unit connected to the
consumption-side feeder thereof through which a current consumption
flows, to output power from the regeneration-side feeder to the
consumption-side feeder through the DC energy interchange unit. The
power control unit also determines the voltage of the DC energy
interchange unit in such a manner as to input/output energy
corresponding to the sum of regenerative power of the
regeneration-side feeder and consumed power of the consumption-side
feeder to/from the secondary battery.
[0012] Other means will be described in the modes for carrying out
the invention.
[0013] The present invention makes it possible to provide a power
converter capable of interchanging and utilizing power regenerated
by an electric motor and to provide a control method for the power
converter.
BRIEF DESCRIPTION OF DRAWINGS
[0014] These and other features, objects, and advantages of the
present invention will become more apparent from the following
description when taken in conjunction with the accompanying
drawings wherein:
[0015] FIG. 1 is a schematic configuration diagram showing a power
converter according to a first embodiment;
[0016] FIG. 2 is a diagram illustrating the details of the power
converter according to the first embodiment;
[0017] FIG. 3 is a graph depicting charging characteristics of a
secondary battery;
[0018] FIG. 4 is a diagram showing a logical configuration of a
power control unit in the first embodiment;
[0019] FIG. 5A is a diagram showing a method of calculating the
charge and discharge amount, and FIG. 5B is a diagram showing a
method of calculating the interchange amount;
[0020] FIG. 6 is a schematic configuration diagram showing a power
converter according to a second embodiment;
[0021] FIG. 7 is a diagram illustrating a logical configuration of
a power control unit in the second embodiment;
[0022] FIG. 8A is a diagram showing a method of calculating the
charge and discharge amount, and FIG. 8B is a diagram showing a
method of calculating the interchanged amount;
[0023] FIG. 9 is a schematic configuration diagram depicting a
power converter according to a third embodiment;
[0024] FIG. 10 is a diagram illustrating a logical configuration of
a power control unit in the third embodiment; and
[0025] FIG. 11 is a diagram showing a relationship between railway
lines and feeders in the third embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Modes for carrying out the invention will hereinafter be
described in detail with reference to the accompanying
drawings.
First Embodiment
[0027] FIG. 1 is a schematic configuration diagram showing a power
converter according to a first embodiment.
[0028] The power converter 1 is connected to a feeder 2-1 (first
feeder) and a feeder 2-2 (second feeder) and mutually converts and
interchanges power between these feeders (2-1, 2-2). Since the
feeders (2-1, 2-2) are configured in like manner, the feeder 2-1
will be described as a representative, and the description of the
feeder 2-2 is therefore omitted. The feeders 2-1, 2-2, . . . will
hereinafter be described simply as feeders 2 when not distinguished
from each other in particular.
[0029] The feeder 2-1 operates a railway vehicle 6-1 with a
single-phase AC of a BT (Booster Transformer) feeding system
supplied from a transformer 3. The feeder 2-1 is connected to the
transformer 3 through an ammeter 4-1 and connected to one terminal
of the power converter 1 so as to exchange power through a
pantograph of the railway vehicle 6-1. A current flowing in the
direction of the feeder 2-1 through the ammeter 4-1 is a supply
current I1a. A voltage applied to the feeder 2-1 is a voltage V1.
Power supplied to the feeder 2-1 is a supply power P1a. Power
interchanged from the feeder 2-1 to the power converter 1 is an
interchange power P1c.
[0030] The transformer 3 has one end connected to a three-phase AC
system (not shown), a first other end connected to the feeder 2-1
through the ammeter 4-1, and a second other end connected to the
feeder 2-2 through an ammeter 4-2. The power converter 1 here
minimizes a power amount supplied from the AC system to thereby
make it possible to minimize power costs of the feeders (2-1, 2-2).
The transformer 3, which is of for example a Scott connection
transformer, converts the voltage of the three-phase AC system to a
single-phase AC of a prescribed voltage and supplies the same to
the feeders 2-1 and 2-2.
[0031] The ammeter 4-1 has one end connected to the transformer 3,
the other end connected to the feeder 2-1, and a sensor output
connected to the power control unit 11 through a communication
line. The ammeter 4-1 measures and outputs the supply current I1a
supplied to the feeder 2-1. The ammeter 4-2 is similar to the
ammeter 4-1. The ammeters 4-1, 4-2, . . . will hereinafter be
described simply as ammeters 4 when not distinguished from each
other in particular.
[0032] A voltmeter 5-1 has one end connected to the feeder 2-1, and
a sensor output connected to the power control unit 11 through a
communication line. The voltmeter 5-1 measures and outputs the
voltage V1 applied to the feeder 2-1. The voltage V1 is an
effective value of the voltage of the single-phase AC. A voltmeter
5-2 is similar to the voltmeter 5-1. The voltmeters 5-1, 5-2, . . .
will hereinafter be described simply as voltmeters 5 when not
distinguished from each other in particular.
[0033] The railway vehicle 6-1 is a vehicle that runs on
electrified railway lines. The railway vehicle 6-1 consumes power
using a motor as a drive source upon its acceleration, applies
brakes using the motor as a generator upon its deceleration, and
regenerates power from kinetic energy in conjunction with it. The
power consumed by the railway vehicle 6-1 is a
consumed/regenerative power P1b. Although a plurality of vehicles
is considered to run along the feeder 2-1, the vehicles are modeled
as the railway vehicle 6-1, and the sum of power of these vehicles
is assumed to be the consumed/regenerative power P1b. When the
consumed/regenerative power P1b is positive, the railway vehicle
6-1 supplies current consumption and consumes power. When the
consumed/regenerative power P1b is negative, the railway vehicle
6-1 supplies a regenerative current and regenerates power. A
railway vehicle 6-2 is also similar to the railway vehicle 6-1. The
railway vehicles 6-1, 6-2, . . . will hereinafter be descried
simply as railway vehicles 6 when not distinguished from each other
in particular.
[0034] The power converter 1 is connected to the sensor output of
the voltmeter 5-1, and the sensor output of the ammeter 4-1. Thus,
the power converter 1 is capable of measuring the voltage V1 of the
feeder 2-1 and the supply current I1a to the feeder 2-1 and
calculating the supply power P1a. Likewise, the power converter 1
is connected to a sensor output of the voltmeter 5-2, and a sensor
output of the ammeter 4-2. Thus, the power converter 1 is capable
of measuring a voltage V2 of the feeder 2-2 and a supply current
I2a to the feeder 2-2 and calculating a supply power P2a.
[0035] The power converter 1 includes a power control unit 11, an
ammeter 12-1 that measures an interchange current I1c, a
transformer 13-1, a power conversion unit 14-1 that mutually
converts power, an ammeter 12-2 that measures an interchange
current 12c, a transformer 13-2, a power conversion unit 14-2 that
mutually converts power, a voltmeter 15 that measures a DC-portion
voltage Vdc, a secondary battery 16, and a DC energy interchange
unit 17.
[0036] The power control unit 11 has a first output terminal
connected to the power conversion unit 14-1 through a communication
line to output a control signal C1, and a second output terminal
connected to the power conversion unit 14-2 through a communication
line to output a control signal C2. The power control unit 11
controls the power conversion unit 14-1 by the control signal C1
and controls the power conversion unit 14-2 by the control signal
C2 to thereby accommodate power between the feeders (2-1, 2-2) and
store surplus energy that cannot be interchanged, in the secondary
battery 16.
[0037] The ammeter 12-1 has one end connected to the feeder 2-1,
the other end connected to the transformer 13-1, and a sensor
output terminal connected to the power control unit 11 through a
communication line. The ammeter 12-1 measures the interchange
current I1c flowing from the feeder 2-1 to the transformer 13-1 and
transmits the measured value of current to the power control unit
11 through the communication line. The ammeter 12-2 is similar to
the ammeter 12-1. The ammeters (12-1, 12-2) will hereinafter be
described simply as ammeters 12 when not distinguished from each
other in particular.
[0038] The transformer 13-1 has one end connected to the feeder 2-1
through the ammeter 12-1 and the other end connected to the power
conversion unit 14-1. The transformer 13-1 converts the voltage V1
of the feeder 2-1 to a prescribed voltage capable of power
conversion by the power conversion unit 14-1. The transformer 13-2
is similar to the transformer 13-1. The transformers 13-1, 13-2, .
. . will hereinafter be described simply as transformers 13 when
not distinguished from each other in particular. The transformer
13-1 is not an essential configuration requirement, and a
configuration may be adopted in which the power conversion unit
14-1 and the feeder 2-1 are directly connected to each other. At
this time, the ammeter 12-1 measures current flowing from the
feeder 2-1 to the power conversion unit 14-1 and transmits the
measured value of current to the power control unit 11 through the
communication line.
[0039] The power conversion unit 14-1 is of, for example, a
single-phase three level converter and has one end connected to the
transformer 13-1, the other end connected to the DC energy
interchange unit 17, and a control terminal connected to the power
control unit 11 through a communication line. The power conversion
units 14-1, 14-2, . . . will hereinafter be described simply as
power conversion units 14 when not distinguished from each other in
particular.
[0040] When the regenerative current flows through the feeder 2-1
and the regenerative power is generated (consumed/regenerative
power P1b is negative), the power control unit 11 instructs the
power conversion unit 14-1 to accommodate the feeder 2-2 with this
regenerative power.
[0041] The power control unit 11 instructs the power conversion
unit 14-1 to determine the DC-portion voltage Vdc in such a manner
that if the SOC (State of Charge) of the secondary battery 16
satisfies a predetermined condition, energy corresponding to the
sum of consumed/regenerative power of the respective feeders 2 is
input to and output from the secondary battery. The power control
unit 11 instructs the power conversion unit 14-1 to determine the
DC-portion voltage Vdc so as to avoid the input/output of energy to
and from the secondary battery 16 if the SOC of the secondary
battery 16 does not satisfy the predetermined condition.
[0042] When the regenerative power is generated in the feeder 2-2
(the consumed/regenerative power P2b is negative), the power
control unit 11 instructs the power conversion unit 14-2 to
accommodate the feeder 2-1 with this regenerative power.
[0043] The power control unit 11 instructs the power conversion
unit 14-2 to determine an interchange current I2c in such a manner
that if the SOC of the secondary battery 16 satisfies the
predetermined condition, energy corresponding to the sum of
consumed/regenerative power of the respective feeders 2 is input to
and output from the secondary battery. The power control unit 11
instructs the power conversion unit 14-2 to determine the
interchange current I2c so as to avoid the input/output of energy
to and from the secondary battery 16 if the SOC of the secondary
battery 16 does not satisfy the predetermined condition.
[0044] The voltmeter 15 has one end connected to the DC energy
interchange unit 17 and a sensor output terminal connected to the
power control unit 11 through a communication line. The voltmeter
15 measures the DC-portion voltage Vdc applied to the DC energy
interchange unit 17 and transmits the measured value of voltage to
the power control unit 11 through the communication line.
[0045] The secondary battery 16 is connected to the DC energy
interchange unit 17 and has an SOC output terminal connected to the
power control unit 11 through a communication line. The secondary
battery 16 receives and outputs surplus energy corresponding to the
sum of the consumed/regenerative power P1b of the feeder 2-1 and
the consumed/regenerative power P2b of the feeder 2-2. The
secondary battery 16 further outputs information on the SOC of the
corresponding battery to the power control unit 11.
[0046] The DC energy interchange unit 17 is connected to the DC
side of the power conversion unit 14-1 and the DC side of the power
conversion unit 14-2. Further, the DC energy interchange unit 17 is
connected to the secondary battery 16 so as to include the
secondary battery 16. The DC energy interchange unit 17 mutually
interchanges energy between the power conversion units (14-1, 14-2)
and the secondary battery 16.
[0047] A current I1d flows from the power conversion unit 14-1 to
the DC energy interchange unit 17.
[0048] A current I2d flows from the power conversion unit 14-2 to
the DC energy interchange unit 17.
[0049] A charge/discharge current I0 flows from the DC energy
interchange unit 17 to the secondary battery 16. When the
charge/discharge current I0 is positive, it is charged into the
secondary battery 16. When the charge/discharge current I0 is
negative, it is discharged from the secondary battery 16.
[0050] FIG. 2 is a diagram showing the details of the power
converter according to the first embodiment.
[0051] The DC energy interchange unit 17 includes a central point
17C grounded, a positive point 17P to which a positive DC voltage
is applied, and a negative point 17N to which a negative DC voltage
is applied. The voltmeter 15-1 is connected to the positive point
17P. The voltmeter 15-2 is connected to the negative point 17N.
[0052] The voltmeter 15-1 has one end connected to the positive
point 17P of the DC energy interchange unit 17. The voltmeter 15-1
measures a positive point voltage Vdcp applied to the positive
point 17P. The voltmeter 15-2 has one end connected to the negative
point 17N of the DC energy interchange unit 17. The voltmeter 15-2
measures a negative point voltage Vdcn applied to the negative
point 17N. The power control unit 11 (refer to FIG. 1) adds the
positive point voltage Vdcp measured by the voltmeter 15-1 and the
negative point voltage Vdcn measured by the voltmeter 15-2 to
calculate a DC-portion voltage Vdc.
[0053] The secondary battery 16 includes battery units (161-1 to
161-6), a secondary battery control unit 162, and switch circuits
(163-1 to 163-6). The battery units (161-1 to 161-6) will
hereinafter be described simply as battery units 161 when not
distinguished from each other in particular. The switch circuits
(163-1 to 163-6) will hereinafter be described simply as switch
circuits 163 when not distinguished from each other in
particular.
[0054] The battery units (161-1 to 161-3) are connected between the
central point 17C and the positive point 17P through the switch
circuits (163-1 to 163-3) and applied with the positive point
voltage Vdcp. The battery units (161-4 to 161-6) are connected
between the negative point 17N and the central point 17C through
the switch circuits (163-4 to 163-6) and added with the negative
point voltage Vdcn. The positive point voltage Vdcp and the
negative point voltage Vdcn are respectively almost half of the
DC-portion voltage Vdc. It is thus possible for the secondary
battery 16 to set its breakdown voltage characteristic to half of
the DC-portion voltage Vdc.
[0055] The secondary battery control unit 162 is connected to
control terminals of the switch circuits (163-1 to 163-6) to switch
on/off these switch circuits (163-1 to 163-6).
[0056] The battery unit 161-3 is connected between the central
point 17C and the positive point 17P through the switch circuit
163-3. The battery unit 161-2 is connected between the central
point 17C and the positive point 17P through the switch circuits
(163-2, 163-3). The battery unit 161-1 is connected between the
central point 17C and the positive point 17P through the switch
circuits 163-1 through 163-3. The battery units (161-4 to 161-6)
and the switch circuits (163-4 to 163-6) are also configured in
like manner. Thus, since the secondary battery control unit 162 can
be separated from the DC energy interchange unit 17 for each
battery unit 161, the battery unit 161 can easily be exchanged upon
the occurrence of a fault in the battery unit 161.
[0057] The secondary battery control unit 162 further measures the
output voltage, output current, temperature and the like of the
respective battery units 161 by various sensors (not shown) to
calculate information of SOC and outputs the same to the power
control unit 11 (refer to FIG. 1).
[0058] FIG. 3 is a graph showing the charging characteristic of the
secondary battery.
[0059] The horizontal axis of the graph indicates SOC of the
secondary battery 16. The vertical axis of the graph indicates
voltage V of the secondary battery 16. The secondary battery
control unit 162 calculates the SOC of each battery unit 161 and
the SOC of the secondary battery 16 based on the output voltage of
each battery unit 161 and the characteristic of the corresponding
graph and then outputs them to the power control unit 11 (refer to
FIG. 1).
[0060] The SOC-voltage characteristic of the secondary battery 16
is almost linear between 30% and 70%. When the SOC is 30%, the
secondary battery 16 outputs a voltage Vmin. When the SOC is 70%,
the secondary battery 16 outputs a voltage Vmax. When the SOC is a
target SOC, the secondary battery 16 outputs a voltage Vt. The
power control unit 11 in the first embodiment controls the SOC of
the secondary battery 16 in such a manner that it falls within at
least a range 30% to 70%. The SOC thereof is however not limited to
it, but may be controlled to fall within an arbitrary SOC
range.
[0061] The power control unit 11 in the first embodiment further
sets the target SOC to approximately 50% in order to cause the
secondary battery 16 to have sufficient charging and discharging
remaining power and prolong the life of each battery unit 11.
[0062] FIG. 4 is a diagram showing the logical configuration of the
power control unit in the first embodiment.
[0063] The power control unit 11 is provided with power calculation
parts (111-1, 111-2), a current calculation part 112, a battery
characteristic calculation part 113, adders/subtractors (114-1,
114-2), proportional integration controllers (115-1, 115-2), and
instantaneous value control parts (116-1, 116-2). The supply
current I1a, interchange current I1c and voltage V1 related to the
feeder 2-1, the supply current I2a, interchange current I2c and
voltage V2 related to the feeder 2-2, the SOC of the secondary
battery 16, and the DC-portion voltage Vdc applied to the DC energy
interchange unit 17 are input to the power control unit 11. Control
signals C1 and C2 are output from the power control unit 111, based
on the input information. The power calculation parts 111-1, 111-2,
. . . will hereinafter be described simply as power calculation
parts 111 when not distinguished from each other in particular. The
instantaneous value control parts (116-1, 116-2) will hereinafter
be described simply as instantaneous value control parts 116 when
not distinguished from each other in particular.
[0064] The consumed/regenerative power P1b of the railway vehicle
6-1 corresponds to the difference between the supply power P1a and
the interchange power P1c to the feeder 2-1. The power calculation
part 111-1 calculates the consumed/regenerative power P1b of the
railway vehicle 6-1 based on the supply current I1a, the
interchange current I1c and the voltage V1 related to the feeder
2-1, and the following equation (1):
P1b=P1a-P1c=(I1a-I1c).times.V1 (1)
[0065] Likewise, the consumed/regenerative power P2b of the railway
vehicle 6-2 corresponds to the difference between the supply power
P2a and the interchange power P2c to the feeder 2-2. The power
calculation part 111-2 calculates the consumed/regenerative power
P2b of the railway vehicle 6-2, based on the supply current I2a,
the interchange current I2c and the voltage V2 related to the
feeder 2-2, and the following equation (2):
P2b=P2a-P2c=(I2a-I2c).times.V2 (2)
[0066] The current calculation part 112 determines based on the sum
of the consumed/regenerative power (P1b, P2b) and the present SOC
whether to perform a charge to the secondary battery 16 or to
perform a discharge therefrom, or whether not to perform either the
charge or discharge of the secondary battery 16.
[0067] For simplification in the following, it is assumed the
amount of the secondary battery 16 is infinite and no restriction
is imposed on charged/discharged power P0. When the supply power
(P1a, P2a) are calculated to be minimized at this time, a
charge/discharge power command value P0* is as represented in the
following equation (3).
[0068] Since the charged/discharged power P0 of the secondary
battery 16 is actually restricted by the amount of the secondary
battery 16, it is necessary to incorporate any constraint
conditions into the equation (3).
P0*=-(P1b+P2b) (3)
[0069] If the sum of the consumed/regenerative power (P1b, P2b) is
positive (power consumption is dominant), and the current SOC is
higher than the target SOC, the current calculation part 112
discharges energy corresponding to the absolute value of the sum of
the consumed/regenerative power (P1b, P2b) from the secondary
battery 16. This is to effectively utilize the energy stored in the
secondary battery 16.
[0070] If the sum of the consumed/regenerative power (P1b, P2b) is
positive (power consumption is dominant), and the current SOC is
less than or equal to the target SOC, the current calculation part
112 does not perform either charge or discharge on the secondary
battery 16. This is to prevent the secondary battery 16 from being
an overcharged state.
[0071] If the sum of the consumed/regenerative power (P1b, P2b) is
negative (regenerative power is dominant) or 0, and the current SOC
is lower than the maximum SOC, the current calculation part 112
charges the energy corresponding to the absolute value of the sum
of the consumed/regenerative power (P1b, P2b) to the secondary
battery 16. This is to avoid the waste of regenerative power.
[0072] If the sum of the consumed/regenerative power (P1b, P2b) is
negative (regenerative power is dominant) or 0, and the current SOC
is greater than or equal to the maximum SOC, the current
calculation part 112 does not perform either charge or discharge on
the secondary battery 16. This is to prevent the secondary battery
16 from being an overcharged state.
[0073] When the energy is charged to or discharged from the
secondary battery 16, the current calculation part 112 calculates a
charging current command value I0* based on the following equation
(4). When either charge or discharge are not performed on the
secondary battery 16, the current calculation part 112 brings the
charging current command value I0* to 0.
I 0 *= P 0 * Vdc = - ( P 1 b + P 2 b Vdc ) ( 4 ) ##EQU00001##
[0074] The battery characteristic calculation part 113 calculates a
DC-portion voltage command value Vdc* at the time that current
corresponding to the charging current command value I0* flows in
the secondary battery 16.
[0075] The adder/subtractor 114-1 subtracts the current DC-portion
voltage Vdc from the DC-portion voltage command value Vdc*. The
proportional integration controller 115-1 performs proportional
integration control on the result of output from the
adder/subtractor 114-1. Thus, the adder/subtractor 114-1 and the
proportional integration controller 115-1 allow the DC-portion
voltage Vdc to converge on the DC-portion voltage command value
Vdc*.
[0076] The adder/subtractor 114-1 and the proportional integration
controller 115-1 calculate a DC-portion voltage command Vdcx based
on the following equation (5). In the equation (5), a proportional
integration control function is represented as a function PI
(Proportional Integral).
Vdcx = P I ( Vdc * - Vdc ) = P I ( f - 1 ( I 0 *) - Vdc ) = P I ( f
- 1 ( - ( P 1 b + P 2 b Vdc ) ) - Vdc ) ( 5 ) ##EQU00002##
[0077] The instantaneous value control part 116-1 generates a
control signal C1 for the power conversion unit 14-1 based on the
DC-portion voltage command value Vdcx. The power conversion unit
14-1 performs a power conversion according to the control signal
C1.
[0078] The current calculation part 112 determines an interchange
power P1c interchanged from the feeder 2-1 to the DC energy
interchange unit 17 and an interchange power P2c interchanged from
the feeder 2-2 to the DC energy interchange unit 17 based on the
consumed/regenerative power (P1b, P2b).
[0079] When the consumed/regenerative power P1b is positive and the
consumed/regenerative power P2b is negative, or when the
consumed/regenerative power P1b is negative and the
consumed/regenerative power P2b is positive, the power of the
smaller one of the absolute value of the consumed/regenerative
power P1b and the absolute value of the consumed/regenerative power
P2b is interchanged from the feeder 2 having regenerative power to
the feeder 2 consuming power.
[0080] If the charged/discharged power P0 of the secondary battery
16 is not 0, the current calculation part 112 further determines
the feeder 2 related to the larger one of the absolute value of the
consumed/regenerative power P1b and the absolute value of the
consumed/regenerative power P2b, and then adds the
charged/discharged power P0 to interchange power from this feeder
2. Thus, the current calculation part 112 determines interchange
current command values (P1c*, P2c*).
[0081] The current calculation part 112 determines an interchange
current command value I2c* based on the determined interchange
power command value P2c*, the voltage V2, and the following
equation (6):
I 2 c *= P 2 c * V 2 ( 6 ) ##EQU00003##
[0082] The adder/subtractor 114-2 subtracts the current interchange
current I2c from the interchange current command value I2c*. The
proportional integration controller 115-2 performs a proportional
integration control on the result of output from the
adder/subtractor 114-2. Thus, the adder/subtractor 114-2 and the
proportional integration controller 115-2 allow the interchange
current I2c to converge on the interchange current command value
I2c*.
[0083] The adder/subtractor 114-2 and the proportional integration
controller 115-2 calculate an interchange current command value I2x
based on the following equation (7). In the equation (7), a
proportional integration control function is represented as a
function PI.
I 2 x = P I ( I 2 c * - I 2 c ) = P I ( P 2 c * V 2 - I 2 c ) ( 7 )
##EQU00004##
[0084] The instantaneous value control part 116-2 generates a
control signal C2 for the power conversion unit 14-2 based on the
interchange current command value I2x. The power conversion unit
14-2 performs a power conversion according to the control signal
C2.
[0085] In the way described above, the power control unit 11
generates the control signals (C1, C2) and interchanges power
between the feeders (2-1, 2-2).
[0086] FIGS. 5A, 5B are diagrams showing the calculation of charge
and discharge amount and the calculation of interchange amount in
the first embodiment.
[0087] FIG. 5A is a diagram showing a method of calculating the
charge and discharge amount.
[0088] If the sum of the consumed/regenerative power (P1b, P2b) is
positive (power consumption is dominant) and the current SOC is
higher than the target SOC, the power converter 1 serves to
discharge energy corresponding to the sum of the
consumed/regenerative power (P1b, P2b) from the secondary battery
16. When the energy is discharged from the secondary battery 16,
the charged/discharged power P0 becomes negative. That is, the
charged/discharged power P0 is represented by the above equation
(3).
[0089] If the sum of the consumed/regenerative power (P1b, P2b) is
positive (power consumption is dominant), and the current SOC is
less than or equal to the target SOC, the power converter 1 does
not perform either charge or discharge on the secondary battery 16.
That is, the charged/discharged power P0 becomes 0.
[0090] If the sum of the consumed/regenerative power (P1b, P2b) is
negative (regenerative power is dominant) or 0, and the current SOC
is lower than the maximum SOC, the power converter 1 serves to
charge energy corresponding to a value obtained by multiplying the
sum of the consumed/regenerative power (P1b, P2b) by (-1) to the
secondary battery 16. That is, the charged/discharged power P0 is
expressed by the above equation (3).
[0091] If the sum of the consumed/regenerative power P1b and P2b is
negative (regenerative power is dominant) or 0, and the current SOC
is greater than or equal to the maximum SOC, the power converter 1
does not perform either charge or discharge on the secondary
battery 16. That is, the charged/discharged power P0 becomes 0.
[0092] FIG. 5B is a diagram showing a method of calculating the
interchange amount.
[0093] If the consumed/regenerative power P1b is positive (power is
consumed), and the consumed/regenerative power P2b is positive
(power is consumed), no power is interchanged between the feeders
2. The power converter 1 determines the interchanged power (P1c,
P2c), based on the charged/discharged power P0. In the drawing,
this case is denoted by (*1).
[0094] If the consumed/regenerative power P1b is positive (power is
consumed), the consumed/regenerative power P2b is negative (power
is regenerated) or 0, and the absolute value of P2b is smaller than
the absolute value of P1b, the power converter 1 takes the
interchange power P2c from the feeder 2-2 as (-P2b) and takes the
interchange power P1c from the feeder 2-1 as (P2b+P0).
[0095] If the consumed/regenerative power P1b is positive (power is
consumed), the consumed/regenerative power P2b is negative (power
is regenerated) or 0, and the absolute value of P1b is smaller than
or equal to the absolute value of P2b, the power converter 1 takes
the interchange power P1c from the feeder 2-1 as (-P1b) and takes
the interchange power P1c from the feeder 2-1 as (P1b+P0).
[0096] If the consumed/regenerative power P1b is negative (power is
regenerated) or 0, the consumed/regenerative power P2b is positive
(power is consumed), and the absolute value of P2b is smaller than
the absolute value of P1b, the power converter 1 takes the
interchange power P2c from the feeder 2-2 as (-P2b) and takes the
interchange power P1c from the feeder 2-1 as (P2b+P0).
[0097] If the consumed/regenerative power P1b is negative (power is
regenerated) or 0, the consumed/regenerative power P2b is positive
(power is consumed), and the absolute value of P1b is smaller than
or equal to the absolute value of P2b, the power converter 1 takes
the interchange power P1c from the feeder 2-1 as (-P1b) and takes
the interchange power P1c from the feeder 2-1 as (P1b+P0).
[0098] If the consumed/regenerative power P1b is negative (power is
regenerated) or 0, and the consumed/regenerative power P2b is
negative (power is regenerated) or 0, no power is interchanged
between the feeders 2. The power converter 1 determines the
interchanged power (P1c, P2c) based on the charged/discharged power
P0. In the drawing, this case is denoted by (*2).
Advantages of First Embodiment
[0099] In the first embodiment described above, the following
advantages (A) through (E) are brought about.
[0100] (A) Between the two feeders 2, the regenerative power is
interchanged and utilized from the feeder 2 through which the
railway vehicle 6 is regenerating the power, to the feeder 2 on the
consumption side, and the power that was not able to be
interchanged is stored in the secondary battery 16. Thus, when each
of the feeders 2 starts consuming or using up power again the power
stored in the secondary battery 16 can be effectively utilized.
[0101] (B) If the SOC of the secondary battery 16 does not satisfy
the predetermined condition, the DC-portion voltage Vdc of the DC
energy interchange unit 17 is determined in such a manner that the
charge/discharge to/from the secondary battery 16 is not performed.
Thus, the secondary battery 16 can be controlled to be a
predetermined charge amount without providing the switches or the
like between the secondary battery 16 and the DC energy interchange
unit 17.
[0102] (C) The power control unit 11 determines the DC-portion
voltage Vdc of the DC energy interchange unit 17 in such a manner
that the energy corresponding to the sum of the
consumed/regenerative power of the two feeders (2-1, 2-2) is input
and output to and from the secondary battery 16. Thus, the power
that cannot be interchanged between the feeders (2-1, 2-2) can be
stored in the secondary battery 16 without providing a voltage
conversion circuit or the like between the secondary battery 16 and
the DC energy interchange unit 17, and the stored power can be
utilized.
[0103] (D) The battery units (161-1 to 161-3) are connected between
the central point 17C and the positive point 17P. The battery units
(161-4 to 161-6) are connected between the central point 17C and
the negative point 17N. The voltage equal to half of the DC-portion
voltage Vdc is applied to each of the battery units 161. Thus, one
having a breakdown voltage equal to half of the DC-portion voltage
Vdc can be used as each battery unit 161.
[0104] (E) Each of the battery units 161 is configured so as to be
separated from the DC energy interchange unit 17 by the switch
circuit 163. Thus, the battery unit 161 can easily be exchanged
upon the occurrence of a fault in each battery unit 161, thereby
making it possible to improve maintainability of the power
converter 1.
Second Embodiment
[0105] FIG. 6 is a schematic configuration diagram showing a power
converter 1A according to a second embodiment. The same components
as those in the power converter 1 of the first embodiment shown in
FIG. 1 are identified by like reference numerals.
[0106] The power converter 1A according to the second embodiment is
connected to feeders (2-1, 2-2) in a manner similar to the power
converter 1 according to the first embodiment and further connected
to a feeder 2-3 (third feeder), and serves to mutually exchange and
share power among these feeders (2-1 to 2-3).
[0107] The feeder 2-1 is different from the feeder 2-1 (refer to
FIG. 1) of the first embodiment and supplied with a single-phase AC
by a transformer 3-1. The transformer 3-1 has one end connected to
an unillustrated three-phase AC system and the other end connected
to the feeder 2-1 via an ammeter 4-1. The configurations other than
those are similar to the feeder 2-1 (refer to FIG. 1) of the first
embodiment.
[0108] The feeders (2-2, 2-3) are similar to the feeder 2-1.
[0109] In addition to the power converter 1 (refer to FIG. 1)
according to the first embodiment, the power converter 1A is
further equipped with an ammeter 12-3 that measures an interchange
current 13c, a transformer 13-3, and a power conversion unit 14-3
that mutually converts power. Furthermore, the power converter 1A
is equipped with a power control unit 11A different from the power
control unit 11 (refer to FIG. 1) of the first embodiment.
[0110] The ammeter 12-3 is similar to the ammeters (12-1, 12-2)
(refer to FIG. 1).
[0111] The transformer 13-3 is similar to the transformers (13-1,
13-2) (refer to FIG. 1).
[0112] The power conversion unit 14-3 is similar to the power
conversion units (14-1, 14-2) (refer to FIG. 1). The power
conversion unit 14-3 is controlled by a control signal C3 to allow
a current I3d to flow through a DC energy interchange unit 17.
[0113] Not limited to the above, feeders 2 of four systems or more
may be connected to the power converter 1A. Further, a secondary
battery 16 may not be connected thereto.
[0114] FIG. 7 is a diagram showing a logical configuration of the
power control unit 11A in the second embodiment. The same
components as those in the power control unit 11 of the first
embodiment shown in FIG. 4 are identified by like reference
numerals.
[0115] The power control unit 11A is further provided with a power
calculation part 111-3, an adder/subtractor 114-3, a proportional
integration controller 115-3, and an instantaneous value control
part 116-3 in addition to the power control unit 11 of the first
embodiment.
[0116] The power control unit 11A is input with a supply current
I1a, an interchange current I1c and a voltage V1 related to the
feeder 2-1, a supply current I2a, an interchange current I2c and a
voltage V2 related to the feeder 2-2, a supply current I3a, an
interchange current I3c and a voltage V3 related to the feeder 2-3,
an SOC of the secondary battery 16, and a DC-portion voltage Vdc
applied to the DC energy interchange unit 17. The power control
unit 11A outputs control signals (C1, C2, C3) based on what is
input thereto.
[0117] A method of calculating the control signal C3 is similar to
the method of calculating the control signal C2 in the first
embodiment (refer to FIG. 4).
[0118] FIGS. 8A, 8B are diagrams showing the calculation of charge
and discharge amount and the calculation of interchanged amount in
the second embodiment.
[0119] FIG. 8A is a diagram showing a method of calculating the
charge and discharge amount.
[0120] If the sum of consumed/regenerative power (P1b to P3b) is
positive (power consumption is dominant) and the current SOC is
higher than a target SOC, the power converter 1A serves to
discharge energy corresponding to the sum of the
consumed/regenerative power (P1b to Pb3) from the secondary battery
16.
[0121] If the sum of the consumed/regenerative power (P1b to P3b)
is positive (power consumption is dominant) and the current SOC is
less than or equal to the target SOC, the power converter 1A does
not perform either charge or discharge of the secondary battery 16.
That is, a charged/discharged power P0 becomes 0.
[0122] If the sum of the consumed/regenerative power (P1b to P3b)
is negative (regenerative power is dominant) or 0, and the current
SOC is lower than the maximum SOC, the power converter 1A serves to
charge energy corresponding to a value obtained by multiplying the
sum of the consumed/regenerative power (P1b to P3b) by (-1) to the
secondary battery 16.
[0123] If the sum of the consumed/regenerative power (P1b to P3b)
is negative (regenerative power is dominant) or 0, and the current
SOC is greater than or equal to the maximum SOC, the power
converter 1A does not perform either charge or discharge of the
secondary battery 16. That is, the charged/discharged power P0
becomes 0.
[0124] FIG. 8B is a diagram showing a method of calculating the
interchanged amount.
[0125] If the consumed/regenerative power (P1b to P3b) is all
positive (power consumption), no power is interchanged between the
feeders 2. The power converter 1A determines the interchanged power
(P1c to P3c) based on the charged/discharged power P0. In the
drawing, this case is denoted by (*3).
[0126] If any of the consumed/regenerative power (P1b to P3b) is
positive (power consumption) and others thereof are negative (power
regeneration) or 0, and the absolute of the sum of regenerative
power is larger than or equal to the absolute value of the sum of
consumed power, the power converter 1A interchanges consumed power
from the respective feeder 2 each related to the regenerative power
to all feeders 2 each related to the consumed power. The power
converter 1A further interchanges power from each feeder 2 related
to the regenerative power according to the charged/discharged power
P0 and thereby charges the secondary battery 16. In the drawing,
this case is described as (P0 dependence).
[0127] If any of the consumed/regenerative power (P1b to P3b) is
positive (power consumption) and the others thereof are negative
(power regeneration) or 0, and the absolute of the sum of the
regenerative power is smaller than the absolute value of the sum of
the consumed power, the power converter 1A interchanges
regenerative power from all feeder 2 through which the regenerative
power is being generated, to the respective feeders 2 each related
to the consumed power. The power converter 1A further interchanges
power from the secondary battery 16 to each feeder 2 related to the
consumed power according to the charged/discharged power P0. In the
drawing, this case is described as (P0 dependence).
[0128] If all the consumed/regenerative power (P1b to P3b) is
negative (power regeneration) or 0, no power is interchanged
between the feeders 2. The power converter 1A determines the
interchanged power (P1c to P3c) based on the charged/discharged
power P0. In the drawing, this case is denoted by (*6).
Advantages of Second Embodiment
[0129] In the second embodiment described above, the following
advantages of (F) through (H) are brought about.
[0130] (F) The power converter 1A mutually interchanges the
regenerative power among at least three systems: feeders (2-1 to
2-3), which reduces a case where the secondary battery needs to be
charged due to the simultaneous occurrence of regenerative power in
plural feeders. The regenerative power generated in the feeders 2,
therefore, can be effectively utilized either when the secondary
battery is small in amount or when no secondary battery is
provided.
[0131] (G) The power control unit 11A compares the absolute value
of the sum of power of the feeders 2 in which consumed power is
being generated and the absolute value of the sum of power of the
feeders 2 in which regenerative power is being generated, and then
takes the smaller one of the absolute values as a power interchange
amount. Thus, even when the feeders 2 of the three systems or more
are connected, it is possible to easily calculate a power
interchange amount.
[0132] (H) One of the power conversion units 14 determines the
DC-portion voltage Vdc of the DC energy interchange unit 17 and the
others determine a current interchanged between the respective
feeders 2. Thus, even when the feeders 2 of the three systems or
more are connected, the DC-portion voltage Vdc can be determined in
such a manner that desired charge/discharge power can be input and
output to and from the secondary battery 16, and the desired power
can be interchanged between the respective feeders 2.
Third Embodiment
[0133] FIG. 9 is a schematic configuration diagram showing a power
converter 1B according to a third embodiment. The same components
as those in the power converter 1A of the second embodiment shown
in FIG. 6 are identified by like reference numerals.
[0134] The power converter 1B according to the third embodiment is
connected with an operation instruction device 7 in addition to the
power converter 1A (refer to FIG. 6) of the second embodiment and
provided with a power control unit 11B different from the power
control unit 11A (refer to FIGS. 6 and 7) of the second
embodiment.
[0135] The operation instruction device 7 is connected to railway
vehicles (6-1 to 6-3) so as to be able to communicate therewith
through cables (not shown) or the like. The operation instruction
device 7 instructs the respective railway vehicles (6-1 to 6-3) to
run, and at the same time, obtains and manages operation
information on the railway vehicles. The operation instruction
device 7 outputs the operation information of the respective
railway vehicles (6-1 to 6-3) to the power control unit 11B of the
power converter 1B. The operation information includes an operation
diagram, the present speed of the railway vehicles (6-1 to 6-3),
and information on their operations (during instruction of their
acceleration or deceleration).
[0136] FIG. 10 is a diagram showing a logical configuration of the
power control unit 11B in the third embodiment. The same components
as those in the power control unit 11A of the second embodiment
shown in FIG. 7 are identified by like reference numerals.
[0137] The power control unit 11B of the third embodiment is
further equipped with a target SOC calculation part 117 in addition
to the power control unit 11A (refer to FIG. 7) of the second
embodiment.
[0138] The target SOC calculation part 117 calculates a target SOC
based on the operation information. When, for example, the present
speed of the respective railway vehicles (6-1 to 6-3) exceed a
prescribed value, and a probability of regenerative power generated
due to the deceleration is high, the target SOC calculation part
117 decreases the target SOC to make it easy to charge the
regenerative power to the secondary battery 16. When the railway
vehicles (6-1 to 6-3) are at a stop, and a probability of consumed
power generated due to the acceleration is high, the target SOC
calculation part 117 further increases the target SOC to make it
easy to accommodate (discharge) the consumed power from the
secondary battery 16.
[0139] Not limited to the examples above, the target SOC
calculation part 117 may determine that a probability of the
regenerative power canceled by the consumed power will be low, and
may increase the target SOC when the target SOC calculation part
117 detects from the operation diagram that the number of the
railway vehicles 6 running on the feeders 2 is low.
[0140] FIG. 11 is a diagram showing a relationship between railway
lines and feeders 2 in the third embodiment.
[0141] The power converter 1B is connected to a feeder 2-1 related
to a railway line from U and O stations, a feeder 2-2 related to a
railway line from the O station to an F station, and a feeder 2-3
related to a railway line from the O station to an M station and
mutually interchanges regenerative power among these three-system
feeders (2-1 to 2-3). The operation instruction device 7 is
connected to the power converter 1B, and the target SOC is adjusted
to be the most appropriate target SOC by the operation instruction
device 7.
Advantages of Third Embodiment
[0142] In the third embodiment described above, the following
advantages of (I) is brought about.
[0143] (I) The target SOC calculation part 117 predicts a
probability of occurrence of the regenerative power based on the
operation instruction information and then increases or decreases
the target SOC. It is thus possible to further charge the
regenerative power to the secondary battery 16.
Modifications
[0144] The present invention is not limited to the above
embodiments and includes various modifications. For example, the
above embodiments are described in detail to explain the present
invention in an easy way to understand, but is not necessarily
limited to one equipped with all constituents described. Some of
constituents of one embodiment can be replaced with constituents of
another embodiment. The constituents of another embodiment can also
be added to the constituents of the one embodiment. The addition,
deletion, and replacement of other constituents can also be
performed on some of the constituents of each embodiment.
[0145] In the respective constitutions, functions, processing
parts, processing means and the like described above, some or all
thereof may be implemented by hardware such as an integrated
circuit or the like. The above respective constitutions, functions
and the like may be implemented using software by causing a
processor to interpret and execute a program for executing the
respective functions. Information about the program, tables, files
and the like that execute the respective functions can be kept in a
recording device such as a memory, hard disk, SSD (Solid State
Drive) or the like, or a recording medium such as an IC card, an SD
card, a DVD (Digital Versatile Disk) or the like.
[0146] In the respective embodiments, there are shown as control
lines and information lines, those considered to be necessary for
convenience of explanation. All the control lines and information
lines are not necessarily shown in terms of products. Actually,
almost all constituents may be considered to have been mutually
connected to each other.
[0147] As the modifications of the present invention, the following
(a) through (c) are illustrated by way of example.
[0148] (a) The single-phase AC of the BT feeding system flows
through the feeders 2 employed in the first through third
embodiments. However, not only this, but the current of a DC
feeding system, an AT (Auto Transformer) feeding system or the like
may flow through the feeders 2. The feeders 2 may also supply power
with a coaxial cable feeding basis.
[0149] (b) The power converter 1 according to the first embodiment
may interchange power so as to suppress power imbalance between the
feeders (2-1, 2-2).
[0150] (c) The feeders 2 employed in the first through third
embodiments supply power to each railway vehicle 6. However, not
only this, but the feeders 2 may supply power to vehicles including
a trolley bus, an electric vehicle, a monorail, a cable car, and a
ropeway.
[0151] While we have shown and described several embodiments in
accordance with our invention, it should be understood that
disclosed embodiments are susceptible of changes and modifications
without departing from the scope of the invention. Therefore, we do
not intend to be bound by the details shown and described herein
but intend to cover all such changes and modifications within the
ambit of the appended claims.
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